Field of the Invention
The invention relates to a method for producing an optoelectronic component, having a laser chip as a light emitter and a lens-coupling optical element for the defined projection of the optical beam generated in the laser chip.
Such optoelectronic components are used especially in optical data and communications technology as light emitting components for coupling the laser light generated into a fiber-optic waveguide.
European Patent EP 0 660 467 B1 describes an optoelectronic component that has a silicon substrate, on which the laser chip is mounted. The laser light, emitted by the laser chip parallel to the surface of the silicon substrate, enters a lens-coupling optical element, by which it is deflected 90.degree. and focused. The lens-coupling optical element has a deflection prism, mounted on the substrate, and a laser chip that is present in the beam path behind the deflection prism.
These optoelectronic components are produced by making composite wafers. First, a silicon wafer acting as a common substrate is provided with suitable metal surface structures. After that, spaced-apart, parallel indentations are etched into the silicon wafer. Prism strips of trapezoidal profile are then placed in these indentations and bonded anodically or by soldering techniques. Next, the laser chips are disposed on the silicon wafer at a defined spacing from the prism strips and secured. The separation into separate components (dicing) is done either before or after the mounting of the laser chips, by sawing the silicon wafer apart along parting lines extending transversely to the prism strips. Finally, the laser chips are secured to the individual deflection prisms created by sawing the wafer apart.
This method has the disadvantage that the object distance, that is, the length of the light path between the emitting laser edge and the principal plane of the lens, cannot always be set with the requisite precision. When there is a structurally specified, fixed spacing between the lens and the deflection prism, the object distance is determined by the spacing between the laser chip and the prism strip. It has been demonstrated in practice that this spacing cannot always be preset with the requisite precision using currently available positioning systems. Furthermore, there are production-dictated variations in the focal length of the lenses. To compensate for the unavoidable positional errors of the laser chips, it is therefore necessary, after the positioning step, to individually measure out the spacings between the laser chips and the deflection prisms, as well as the focal lengths of the lenses used, and then to assign the respective laser chip a lens that fits it, in order to attain the desired focusing of the laser beam in a predetermined image plane.